This invention relates in general to keg tapping devices and deals more particularly with an improved tavern unit for use with a keg unit permanently or semi-permanently connected to a keg to dispense liquid from the keg. The present invention relates more specifically to a universal tavern unit for a keg tapping device of the type shown and described in my U.S. Pat. No. 3,228,413 for Keg Tapping Device, issued Jan. 11, 1966, and assigned to the assignee of the present invention. The device of the aforementioned patent includes a keg unit and a tavern unit for connection thereto. The tavern unit has inlet and outlet passageways which communicate with the interior of a keg when the keg unit is attached to the keg and the tavern unit is connected to the keg unit. The inlet passageway is partially defined by an inlet tube which has a pressure relief valve mounted thereon for automatically bleeding gas from the keg to maintain pressure in the keg at a safe level in the event that pressure tends to rise above such level. It is also customary to provide a check valve at the inlet end of the latter tube to prevent retrograde gas or liquid flow in a conduit connected to the inlet tube and to a source of gas under pressure. The pressure relief valve and check valve are considered essential elements in a single keg dispensing system; that is, a system wherein the tapping device is connected to a single keg and to a source of gas under pressure for dispensing beer or the like from the keg to a tap or spigot. However, in a tavern or restaurant where a large quantity of beverage must be dispensed in a relatively short time, tapping devices of the aforedescribed type may be used in a multiple keg or series connected system which assures a constant supply of beverage for a prolonged period without interruption for removal and replacement of empty kegs. Such a system generally comprises a plurality of kegs or barrels each of which has a tapping device of the aforedescribed general type connected thereto. The tapping devices on the kegs are connected together in series with each other between a source of gas under pressure and a tap or spigot. In a beverage dispensing system of the aforedescribed type, it is generally desirable to use only one check valve on the tapping device associated with the keg nearest the gas pressure source. The check valves associated with the remaining tapping devices are preferably removed from the other tavern units which comprise the system to permit unobstructed fluid flow through the lines connecting the various kegs and to the tapping spigot. However, if the unnecessary check valves are not removed, when the system is installed, malfunction or abnormal flow at the spigot may result. Since it is usually difficult for one not thoroughly familiar with such a system to locate the source of the latter problem, the system may remain out of operation until the condition is corrected by a qualified repairman. Further, if the tavern unit has a relief valve permanently connected thereto when the tavern unit is used in a multi-keg system with other tavern units of like kind, the system will contain a plurality of unrequired relief valves, all of which add unnecessary expense to the installation. Accordingly, it is the general aim of the present invention to provide a universal tavern unit which may be adapted for use in either a single keg or multi-keg dispensing system to simplify installation of a system and minimize its cost.